Deflection circuits



Dec. 10, 1946. chSMlTH 2,412,542

DEFLECTI ON CIRCUITS Filed May 25, 1944 INVENTOR.

nyyrffgm ATTORNEY Patented Dec. 10, 1946 UNITED STATES PATENT OFFICEDEFLECTION CIRCUITS Lester C. Smith, Westmont, N. J., assignor to RadioCorporation of America, a corporation of Delaware Claims. 1

This invention relates to an improvement in cathode ray beam deflectiongenerators for use in oscilloscopic or other related apparatus.

As is well known to those skilled in the art, a cathode ray oscilloscopeincludes, in general, a circuit arrangement for causing the cathode raybeam that is generated in a cathode ray tube to be repeatedly deflectedacross the viewing screen of the cathode ray tube in a horizontaldirection, while the transient or voltage variation to be observed isgenerally applied, after appropriate amplification, to the verticaldeflecting plates of the cathode ray tube to cause the beam to bedeflected in a vertical direction across the screen of the cathode raytube. The horizontal deflection circuit is generally so constructed asto permit the deflection rate to be varied within very wide limits inorder that the rate at which the cathode ray beam is deflectedhorizontally (generally in a linear manner) may be varied to permitconvenient inspection of the trace regardless of the rate of variationof the voltage variations under observation.

In normal use of the cathode ray oscilloscope, the horizontaldeflections of the cathode ray beams are continued at a predeterminedrate, and if the voltage variations under observation reoccur at apredetermined rate, a proper choice of the recurrence rate of thehorizontal deflection of the cathode ray beam will cause a substantiallystationary trace or image to appear on the screen of the cathode raytube. 7

There are instances, however, when the voltage variation or phenomenonunder observation is not regularly recurrent, and under thesecircumstances it is not possible to relate the horizontal deflectionrate to the occurrence frequency of the voltage variations underobservation, with the result that a substantially stationary imagecannot be produced on the viewing screen of the cathode ray tube.

Under conditions where the transient voltage variation to be observed isnot regularly recurrent, cathode ray Oscilloscopes have been used inwhich a so-called single sweep operation is possible, and under thesecircumstances the cathode ray beam is generally biased to remainnormally stationary, with circuit arrangements such that when atransient condition is impressed upon the apparatus to cause verticaldeflections of the cathode ray beam, a simultaneous single sweep orsingle horizontal deflection of the cathode ray beam is brought about.

When the cathode ray beam is normally biased in a stationary conditionat the right hand side of 2 the viewing screen, the cathode ray beammust first be quickly deflected to the left side of the screen beforethe sweep or relatively slower deflection can take place from the leftside of the screen to the right in the usual manner. This interval inreturning the cathode ray beam to the left side of the screen prior toits deflection at a predetermined rate occupies some period of time, andaccordingly it is possible that a portion of the voltage variations tobe observed will be lost during this return time interval. Should thetransient condition prevail for a relatively short space of time, anappreciable portion of the voltage variations to be observed may beentirely lost even though the deflection rate may be increased to arelatively high speed.

Furthermore, in such devices as have heretofore been used, the circuitarrangement for causing the single sweep action has not been whollysatisfactory since in many cases a rather intense triggering potentialis required to cause operation of the single sweep mechanism. Thisinitial intense impulse is in many instances not available, since it isnot uncommon for a transient condition to commence at relatively lowamplitude, and under such circumstances the single sweep circuitarrangement would not respond until the transient condition haspersisted for an appreciable portion of its interval.

Also, in other single sweep circuits, the selection of sweep rates isordinarily adjustable only in fixed steps or over a relatively narrowrange and the signal under observation must be recurrent within certainfixed time limits.

In order to overcome these difficulties, the present invention providesa single sweep circuit arrangement whereby the cathode ray beam isnormally biased in a stationary position at the left side of the screenso that upon the occurrence of a transient condition or a voltagevariation to be observed, the cathode ray beam is in immediate conditionto start its useful deflection from the left to the right side of theviewing screen. Furthermore, in accordance with the present inventionand by reason of the particular single sweep circuit arrangementprovided therein, the single sweep operation may be initiated on arelatively low intensity voltage variation in order that virtually allof the transient condition may be effective in producing an observablesignal trace on the viewing screen of the cathode ray tube. In additionto these provisions, the single sweep circuit arrangement also providesmeans whereby the rate of sweep may be continuously varied within widelimits to cause the cathode ray beam to traverse the screen at anydesired rate, and furthermore, by means of the present circuitarrangements the transient to be observed may reoccur as rapidly as20,000 or more times per secnd or at any slower rate, even to a singleisolated instance. Regardless of the duration or occurrence rate of thetransient the circuit arrangernent can be adjusted to produce a singledeflection of the cathode ray beam for each individual transient and bycontrolling the rate of deflection the trace produced by the transientcan be caused to occupy a substantial portion of the useful area of theobservation screen.

One of the purposes of the present invention resides, therefore, in theprovision of a new and improved single sweep circuit arrangement for usein connection with cathode ray oscilloscope apparatus.

Another purpose of the present invention resides in the provision of asingle sweep circuit arrangement for a cathode ray oscilloscope in whichthe cathode ray beam is normally biased in its returned position, thereturn deflection of the cathode ray beam taking place immediatelyfollowing each single sweep deflection rather than immediately prior toeach single sweep deflection.

Still another purpose of the present invention resides in the provisionof means whereby the single sweep deflection circuit may be caused torespond to relatively low intensity voltage vari ations derived from theapplied transient to be observed.

Still a further purpose of the present invention resides in theprovision of a single sweep deflection circuit for use with a cathoderay oscilloscope in which the rate of deflection during each deflectioncycle may be varied within very wide limits.

Another purpose of the present invention resides in the provision of asingle sweep deflection circuit for use in an oscilloscope in whichproper single sweep operation will result regardless ofthe repetitionfrequency of the transient, or even in the absence of any repetition.

Still other purposes and advantages of the present invention will becomemore apparent to those skilled in the art from the following detaileddescription of the invention, particularly when considered in connectionwith the drawing, wherein the single figure represents a preferred formof the present invention.

Referring now to the drawing, the single sweep deflection circuitincludes two electron discharge tubes l8 and i2, each of which includesat least a cathode, a control electrode and an anode.

The cathode it of tube i0 is connected to ground by way of cathoderesistance I6, in series with which may be connected a small inductanceH3. The control electrode 20 of tube I0 is connected to input terminal22 by way of coupling condenser 24 and relatively small resistance 26.The condenser 24 and resistance 26 are connected in series, and thejunction of these elements is connected to ground by Way of gridresistor 28. The anode 53 of tube ill is connected to positive terminal32 (to which anode supply voltage is applied) by way of load resistance34.

For coupling tube ID to tube I2, a plurality of selectable couplingcondensers 36, 31, and 38 are employed, and one terminal of each ofthese condensers is connected to the anode 30 of tube It]. The otherterminal of each of these condensers is connected to a selector switch40 in order that one of the condensers may be individually selected andincluded in the circuit. A movable arm or" the selector switch 48 isconnected to the control electrode 32 of tube 12 by way of smallresistance 34. A grid resistance is connected between the cathode l6 oftube Ill and the junction of selector switch 48 and resistance 44. Thisgrid resistance includes preferably a fixed resistance element 46 and avariable resistance elernent 48. The cathode 50 of tube I2 is shownconnected to the cathode Hi of tube it by way of resistance 52, althoughthis resistance is not essential in all instances. This resistance 52 issmall as compared with the cathode resistance IG, and if included in thecircuit provides some automatic biasing of tube l2 relative to thebiasing of the cathode M of tube In. The cathode resistance i6 isnaturaly common to both tubes.

A plurality of selectable sweep condensers 54, 55 and 59 are includedbetween an anode 58 of tube E2 and ground. One terminal of each of thecondensers is connected to the anode 58 whereas the other terminal of aselected one of the condensers may be connected to ground by way ofselector switch til. For proper operation of the system, the series ofcondensers 54, 55 and 58 is preferably about ten times the capacity ofthe series of condensers 36, 3?, and 38, and the two selector switches40 and 69 are preferably ganged together for simultaneous operation.

The anode 53 of tube i2 is connected to positive terminal 3?. by Way offixed resistance 62 and variable resistance 64. The variable resistanceas included in the anode circuit of tube l3. and the variable resistance48 connected in the grid circuit of tube l2 are preferably gangedtogether in order that their values may be simultaneously controlled.Variation in the size of resistance 64 affects the charging rate of theselected condenser 56, 55 or 56 and accordingly provides a Vernier orfine adjustment for determining the sweep rate and length of sweep,while simultaneous adjustment of resistance 48 changes duration ofchargin cycle and thereby determines total amount of charge of potentialof anode 58. The coarse adjustment is, of course, determined by theparticular pair of condensers selected by the selector switches ti! and53.

The voltage variations appearing across the selected condenser 54, 55 or56 provide the. desired sweep potential variations, and accordingly theoutput may be derived from terminals 65 connected between ground and theanode 58 of tube l2.

In general, the deflection voltage variations are produced by a chargingof the condenser selected by selector switch 553 from positive terminal32 over resistances 54 and 62. As long as the condensers are notpermitted to charge to the full applied position potential, asubstantially linear charge condition or voltage variation may beproduced at the anode 53 of tube [2. When the charge has reached apredetermined proportion, the tube i2 is permitted to conduct, whichresults in a substantially instantaneous discharge of the selectedcondenser through tube l2. During this discharge interval, current flowsthrough tube I2 and, accordingly, through cathode resistances 16 and 52.The voltage drop produccd across resistance i6 therefore drives thecathode of tube ill in a positive direction, resulting in an increase inthe bias of tube i8 which causes this tube to become non-conductive. Forsingle sweep operation, this condition of conduction through tube i2should persist, and the substantiallynon-conduction condition of tubeIll should also persist.

When it is desired to permit a charge to accumulate on one of theselected condensers 54, 55 or 56, and accordingly, to cause a.deflection of the cathode ray beam, a positive triggering impulse isapplied to the control electrode 20 of tube I which renders tube I0conductive and the potential at the anode of tube I6 is, therefore,driven in a negative direction. This negative impulse in then applied byWay of one of the selected condensers 36, 31 or 33 to the controlelectrode 42 of tube I2 to render tube I2 non-conductive. During itsnon-conductive condition, the selected condenser 54, 55 or 56 ispermitted to charge through resistances 62 and 64 and, accordingly asweep deflection potential variation is developed. Immediately followingthe sweep deflection tube I2 discharges the particular charged condenserand renders tube Ill non-conducting, or substantially so, thus preparingthe circuit for the next operation cycle.

In order that this desired cycle of operation may be assured and inorder that the circuit may be responsive to relatively low intensitytriggering potentials applied to the control electrode 20 of tube ID,the circuit includes, in addition to the elements above described,diodes or unidirectional conducting devices 68 and I0. Each of thesediodes includes at least a cathode and an anode.

For maintaining proper operating potential on the electrodes of thediodes, two potentiometers I2 and I4 may be connected in series betweenpositive terminal 32 and ground or the negative anode supply voltage.The anode I6 of nected to the anode 30 of tube III, while the oathode I8element is connected to the movable contact of the potentiometer I2. Thecathode 86 of diode I0 is connected to the anode 58 of tube I2, while.the anode 82 of diode I0 is connected to the movable contact ofpotentiometer I4. The diode I0 operates primarily to assure a continuedconducting condition of tube I2 to maintain tube I0 substantiallynon-conducting in the absence of any triggering or synchronizingimpulses, and to limit the amplitude of excursion of anode 56 in thenegative direction (less positive). Furthermore, the diode 68 causes theefiective gain of tube III to be reduced to a very low value during itsperiods of substantial inactivity. With the diodes 68 and I3 included inthe circuit, the operation of the single sweep arrangement hereindescribed will now be discussed.

In describing the operation of the system it will be assumed that theselected one of the condensers 54, 55 or 56 has been discharged byconduction through tube I2, and that the tube is maintained in aconducting condition by reason of the presence of the diode H3. Theresistance values of the resistance 62 and the potentiometer 64 isfairly high and, as a result, if the diode It! were not included in thecircuit, the potential of the anode of tube I2 would drop to a,relatively low amount determined primarily by the impedance of the tubeI2. It will be noticed, however, that the anode of the diode I6 isconnected to a movable contact along the potentiometer 14 whichmaintains the anode 82 of the diode I0 at a predetermined and adjustablepositive potential relative to ground.

As soon as the anode 58 of tube l2 drops below this positive potential,the cathode 80 of the diode I6 then becomes negative with respect to theanode 62 and current is permitted to flow through the diode 10. This, ineffect, forms a parallel diode 68 is contial determined by the settingof the movable contact along the potentiometer I4. Tube I2 will,therefore, continue to conduct and the selected condenser 54, 55 or 56will be maintained in a discharged condition.

Furthermore, since the ungrounded terminal of the selected condenser isconnected to the anode 58 of tube I2, an adjustment of the movablecontact along potentiometer I4 will determine the potential to which theparticular selected condenser is discharged. While tube I2 remains inthis conducting condition, tube In is substantially non-conducting, andsince the diode 68 is, in effect, connected in parallel with the loadimpedance 34 of tube N3, the gain of tube I0 is reduced to a very lowvalue. It will be observed that the anode 16 of diode 68 is connected tothe anode 3B of tube I0, whereas the cathode I8 of diode 68 is connectedto a movable point along potentiometer I2.

When a positive triggering impulse is applied to terminal 22, tube I0 isrendered momentarily conducting since the bias on the tube is reduced,and this conducting condition causes the potential at the anode 30 oftube I0 to change in a negative direction which removes the effect ofthe diode 68 and subsequently causes a negative impulse to be applied byway of a selected coupling condenser 36, 31 or 38 to the controlelectrode 42 of tube 12. This negative impulse then increases the biason tube I2, decreasing cathode current of tube I2, reducing voltage dropacross resistor I6, which decreases bias on tube I0. This increasescurrent through tube I0, which causes further change in potential ofanode 36 in a nega- .tive direction, with the result that tube I2 isrendered non-conducting, and the selected condenser 54, or 56 ispermitted to charge through resistances 62 and 64.

In the absence of any circuit elements, the selected condenser wouldnaturally charge to the full potential applied to terminal 32 in thelength of time determined by the time constant of the circuit, butconsiderably before any such charge condition has been reached, tube I2is again rendered conductive to discharge the selected condenser. As iswell known tothose skilled in the art, the charging of a condenserthrough a resistance is approximately linear for a time interval smallcompared to l/RC, and for producing linear deflections of a cathode rayit is desirable to not permit the condenser to operate appreciablybeyond the substantially linear portion of its charge curve. The lengthof time that the selected condenser 54, 55 or 56 is permitted to chargeis then determined by the value of resistances 46 and 68, the latter ofwhich is made adjustable.

During the charge of the selected condenser 54, 55 or 56, the controlelectrode 42 of tube I2, which was driven in a negative direction(beyond cut-01f) by the impulse from tube In, gradually changes itspotential in a postive direction by reason of a discharge of theselected condenser 3'6, 31 or 38 through resistances 46 and 48 therebyreducing the bias on tube I2. After the control electrode potential oftube I2 has changed in a positive directionby a predetermined amount,the tube I2 is again rendered conductive and a regenerative cycle occursthe reverse of that described above, which culminates in the controlelectrode Q2 of tube l2 being driven to zero bias, or slightly positive.Tube l2 then begins to discharge the selected condenser 56, 55 or 56. Asstated above, the length of time that grid 42 is negative beyond cut-offis determined by the time constant of resistances 4E and 68' togetherwith the particular selected condenser 38, 31 or 38.

After tube I2 has been rendered conductive, the selected condenser 5 55or 53 is then discharged and in the absence of a further triggering orsynchronizing impulse, tube i2 remains conductive and the selectedcondenser remains discharged. The circuit remains in this quiescentcondition until a further positive triggering impulse is applied to tubeiii, and upon such an application the cycle is again repeated.

Since the selected condenser 5:1, 55 or 55 is only permitted to chargeto a small percent-age of the potential applied to terminal 32, andsince the particular condenser is discharged substantiallyinstantaneously through tube 112, a sawtooth shaped voltage variationmay be derived between the anode of tube l2 and a point of fixedpotential. Accordingly, potential variations of sawtooth wave form maybe obtained from terminal 65. The slope of the produced sawtooth wave,as well as its time duration, may be determined by proper selection ofthe condensers by means of the selector switches 26 and 60 which arepreferably ganged together, and a Vernier or fine adjustment of theslope and time duration may be accomplished by a variation in the valuesof the resistances 48 and 64, the controls for these values being alsopreferably ganged together. The signal output intensity from terminals56 and the linearity of wave form remain substantially constantregardless of the chosen sweep rate.

By means of the circuit arrangement and the controls associatedtherewith, it is therefore possible to produce potential variationssuitable for deflecting a cathode ray beam in a linear manner, the rateof sweep being controlled within wide limits so that the cathode raybeam may be caused to traverse a screen relatively slowly or veryrapidly, the traversal being maintained substantially linear regardlessof the particular rate.

Since the circuit arrangement described is not periodic in operation,but is instead aperiodic, these voltage variations of sawtooth wave formare not regularly recurrent but are produced only as a result of theapplication of a positive triggering or synchronizing impulse to thecontrol electrode o1" tube I ii. The circuit shown can, however,conveniently be converted to a periodic sweep generator by merelychanging the value of the resistance I 6. Under such conditions thediodes 88 and 10 are not necessary.

Due tothe critical biasing of tube iii and the presence of diode 68, avery low intensity triggering or synchronizing impulse is eifective tocause operation of the circuit and thereby to produce a voltagevariation for deflecting the cathode ray beam in order that anoscillographic trace of a transient condition may be produced.

From the above description it may be seen, therefore, that the presentinvention differs from usual single sweep deflection arrangements inthat a voltage variation for deflection is produced such that thecathode ray beam of the tube is normally biased in a position at thestarting side (generally the left hand side) of the viewing screen.Under these circumstances, the beam is immediately in condition to beginits useful deflection across the screen of the viewing tube as soon as atriggering impulse is applied. In the usual single sweep deflectioncircuit, the application of a synchronizing or triggering impulse firstcauses the usual return of the cathode ray beam which is immediatelyfollowed by the useful defiection stroke. In the present invention,however, the application of a triggering or synchronizing impulse firstcauses the useful traversal or deflection of the cathode ray beam whichis immediately followed by the return deflection stroke.

The application of a triggering or synchronizing impulse in the presentinvention, therefore, does not first result in a discharge of the sweepcondenser, as is the usual case, but instead immediately results in thecharging of the sweep condenser, the charged condition being immediatelyfollowed by the discharge cycle, at which point the system remainsinactive until a further triggering or synchronizing impulse is applied.For this reason there is no time delay in the immediate presentation ofthe oscilloscope trace, and since the deflection circuit describedherein will respond to very low intensity triggering impulses, it ispossible to produce on the screen of the cathode ray oscilloscope anentire transient condition even though the initial portion of thetransient condition is of low amplitude. Furthermore, should thetransient condition persist for a very short length of time, the entiretransient condition is still presented on the screen of the oscilloscopeby reason of the fact that no portion of the time occupied by thetransient condition is consumed in the return deflection of the cathoderay beam.

Various alterations and modifications may be made in the presentinvention without departing from the spirit and scope thereof, and it isdesired that any and all such alterations and modifications beconsidered within the purview of the present invention, except aslimited by the hereinafter appended claims.

Having now described my invention, what I claim is:

1. A circuit arrangement for producing single sweep deflection voltagevariations for a cathode ray oscilloscope in response to individualtriggering impulses comprising a first and second electron dischargetube each having a cathode, a control electrode and an anode, meansincluding a common impedance element for connecting the cathodes of thetubes to a point of fixed potential, and means for applying thetriggering impulses to the control electrode of the first electrondischarge tube, means including a load impedance for maintaining theanode of the first electron discharge tube positive with respect to itsassociated cathode so that potential variations are present at the anodeof said tube in response to the applied triggering impulses, means forcoupling the anode of said first electron discharge tube to the controlelectrode of said second electron discharge tube, means including anadjustable resistance for maintaining the anode of the second electrondischarge tube positive with respect to its associated cathode, acondenser connected between the anode of the second electron dischargetube and a point of fixed potential so that the condenser may be chargedthrough the resistance associated with the second electron dischargetube and so that the condenser may be discharged by said second electrondischarge tube in response to potential variations applied to thecontrol electrode of said tube from said first electron discharge tube,a first diode including a cathode and an anode, means for connecting theanode of said first diode to the anode of said first electron dischargedevice, and means for applying a predetermined positive potential to thecathode of said first diode so that said first electron discharge tubemay be maintained in a substantially non-conducting condition in theabsence of a positive triggering impulse, a second diode including acathode and an anode, means for connecting the cathode to the anode ofsaid second electron discharge tube, and means for applying apredetermined positive potential to the anode of said second diode inorder to maintain a conductive condition of said second electrondischarge tube in the absence of applied potential variations wherebysingle sweep potential variations may be produced at the anode of saidsecond electron discharge tube in response to the application of a,triggering impulse to the first electron discharge tube.

2. A circuit arrangement for producing single sweep deflection voltagevariations for a cathode ray oscilloscope in response to individualtriggering impulses comprising a first and second electron dischargetube each having a cathode, a control electrode and an anode, meansincluding a common impedance element for connecting the cathodes of thetubes to a point of fixed potential, means for applying the triggeringimpulses to the control electrode of the first electron discharge tube,means for maintaining the anode of the first electron discharge tubepositive with respect to its associated cathode so that potentialvariations are present at the anode of said tube in response to theapplied triggering impulses, means for applying the produced potentialvariations to the control electrode of said second electron dischargetube', means including a resistance for maintaining the anode of thesecond electron discharge tube positive with respect to its associatedcathode, an electron storage element connected between the anode of thesecond electron discharge tube and a point of fixed potential so thatthe electron storage element may be charged through the resistanceassociated with the second electron discharge tube and discharged bysaid second electron discharge tube in response to potential variationsapplied thereto, a first unilateral conducting device including acathode and an anode, means for connecting the anode of said firstunilateral conducting device to the anode of said first electrondischarge device, and means for applying a predetermined positivepotential to the cathode of said first unilateral conducting device, asecond unilateral conducting device including a cathode and an anode,means for connecting the cathode to the anode of said electron dischargetube, and means for applying a predetermined positive potential to theanode of said second unilateral conducting device whereby single sweeppotential variations may be produced at the anode of said secondelectron discharge tube in response to the application of a triggeringimpulse to the first electron discharge tube.

3. A circuit arrangement for producing single sweep deflection voltagevariations for a cathode ray oscilloscope in response to individualtriggering impulses comprising a first and second electron dischargetube each having a cathode, a control electrode and an anode, meansincluding a common impedance element for connecting the cathodes of thetubes to a point of fixed potential, means for applying the triggeringimpulses to the control electrode of the first electron discharge tube,means including a load impedance for maintaining the anode of the firstelectron discharge tube positive with respect to its associated cathodeso that potential variations are present at the anode of said tube inresponse to the applied triggering impulses, means for applying theproduced potential variations to the control electrode of said secondelectron discharge tube, means including a load resistance formaintaining the anode of the second electron discharge tube positivewith respect to its associated cathode, an electron storage elementconnected between the anode and the second electron discharge tube and apoint of fixed potential 50 that the electron storage element may becharged through the load resistance associated with the second electrondischarge tube and discharged by said second electron discharge tube inresponse to potential variations applied thereto, a first unilateralconducting device effectively connected in parallel with the said loadimpedance so that said first electron discharge tube may be maintainedin a substantially non-conducting condition in the absence of a positivetriggering impulse, a second unilateral conducting device efiectivelyconnected in parallel with the said load resistance in order to maintainconducting condition of said second electron discharge tube in theabsence of the potential variations produced at the first electrondischarge tube whereby single sweep potential variations may be producedat the anode of said second electron discharge tube in response to theapplication of a triggering impulse to the first electron dischargetube.

4. A single sweep deflection generator including a first and secondelectron discharge tube each including a cathode, a control electrodeand an anode, means including a common cathode impedance for connectingthe cathodes of the tubes to a point of fixed potential, means includinga load impedance for maintaining the anode of the first electrondischarge tube positive with respect to its cathode, means for applyingtriggering potentials extending in a positive direction to the controlelectrode of the first electron discharge tube to produce correspondingpotential variations extending in a negative direction at the anode ofsaid tube, means to assure a substantially non-conducting condition ofthe first electron discharge tube in the absence of a triggering impulsecomprising a diode having an anode and a cathode, means for effectivelyconnecting the diode in parallel with the load impedance of the firstelectron discharge tube, means including an adjustable resistance formaintaining the anode of the second discharge tube positive with respectto its cathode, a condenser connected between the anode of said secondtube and a point of fixed potential, so that the condenser may becharged through said adjustable resistance and discharged by said secondtube in response to the application of the voltage variations from saidfirst electron discharge tube to the control electrode of saidsecondelectron discharge tube, and means to assure a conducting condition atsaid; second electron discharge tube in the absence of an appliedpotential variation to the control electrode of saidtube comprising adiode having a cathode and an anode, and means for connecting the diodeeffectively in parallel with the adjustable resistance whereby thecondenser will be charged through said resistance to a predeterminedpotential level and immediately be discharged by said second electrondischarge tube in response to the application of a single triggeringimpulse 1 l to the control electrode of the first electron dischargetube to produce single sweep potential variations at the anode of saidsecond tube.

5. A single sweep deflection generator including a first and secondelectron discharge tube each including a cathode, a control electrodeand an anode, means including a common cathode impedance for maintainingthe cathode of the tubes at substantially the same potential, meansincluding av load impedance for maintaining the anode of the firstelectron discharge tube positive with respect to its cathode, means forapplying triggering potentials extending in a predetermined direction tothe control electrode of the first electron discharge tube to producepotential variations at the anode of said tube, means to normally assurea substantially non-conducting condition of the first electron dischargetube comprising a diode, means for effectively connecting the diode inparallel with the load impedance of the first electron discharge tube,means including a resistance for maintaining the anode of the seconddischarge tube positive with respect to its cathode, a condenserconnected between the anode of said second tube and a point of fixedpotential so that the condenser may be charged through said resistanceand discharged by said second tube in response to the application of theproduced voltage variations to the control electrode of said secondelectron discharge tube, and means to normally assure a conductingcondition at said second electron discharge tube comprising a diode, andmeans for connecting the diode effectively in parallel with saidresistance whereby the condenser will be gradually charged to apredetermined potential level and immediately quickly discharged by saidsecond electron discharge tube in response to the application of asingle triggering impulse to the control electrode of the first electrondischarge tube to produce single sweep potential variations at the anodeof said second tube.

6. A sin le sweep deflection generator including a first and secondelectron discharge tube each including a cathode, a control electrodeand an anode, means includin a common cathode impedance for connectingthe cathodes of the tubes to a point of fixed potential to maintain thecathodes at substantially the same potential means including a loadimpedance for maintaining the anode of the first electron discharge tubepositive with respect to its cathode, means for applying a triggeringpotential to the control electrode of the first electron discharge tubeto produce a corresponding potential variation at the anode of saidtube, means including a resistance for maintaining the anode of thesecond discharge tube positive with respect to its cathode, a condenserconnected between the anode of said second tube and a point of fixedpotential, so that the condenser may be relatively slowly chargedthrough said resistance and quickly discharged by said second tube inresponse to the application of the produced voltage variation to thecontrol electrode of said second electron discharge tube, and means toassure aperiodic operation of the deflection generator and to normallymaintain a conducting condition at said second electron discharge tubein the absence of an applied potential variation to the controlelectrodeof said tube comprising a diode, and means for effectively connectingthe diode in parallel with the resistance whereby the condenser will becharged to a predetermined potentiallevel and will be im- 12 mediatelydischarged by said second electron discharge tube in response to theapplication of a single triggering ilnpulse to the control electrode ofthe first electron discharge tube thereby to produce a single sweeppotential variation at the anode of said second tube.

7. A single sweep deflection generator including a first and secondelectron discharge tube, each tube including a cathode, a controlelectrode and an anode, means for maintaining the cathodes atsubstantially the same potential including a common impedance forconnecting the cathodes to a point of fixed potential, means forapplying individual triggering impulses to the control electrode of thefirst electron discharge tube to produce potential variations at theanode of said tube, means for applying the produced potential variationsto the control electrode of the second electron discharge tube, meansincluding an adjustable resistance for maintaining the anode of thesecond electron discharge tube positive with respect to its associatedcathode, a condenser connected between the anode of the second electrondischarge tube and a point of fixed potential whereby the condenser maybe relatively slowly charged through theadjustable resistance andquickly discharged by said second electron discharge tube, a. first andsecond unilateral con ductingdevice individually associated withtheanode circuit of the electron discharge tubes to assure a normallysubstantially non-conducting condition of the first electron dischargetube and a normally conducting condition of the second electrondischarge tube so that upon the application of an individual triggeringimpulse to the control electrode of the first electron discharge tubethe said condenser will be charged to a predetermined potential valueand will be immediately discharged by said second electron dischargetube thereby assuring aperiodic operation of the circuit to producesingle sweep potential variations at the anode of the second electrondischarge tube in response to applied triggering impulses to the firstelectron discharge tube.

3. A single sweep deflection generator including a first and secondelectron discharge tube, each tube including a cathode, a controlelectrode and an anode, means for maintaining the cathodes of said tubesat substantially the same potential, means for applying individual andsporadic triggering impulses. to the control electrode of the firstelectron discharge tube to. produce potential variations at the anode ofsaid tube, means for applying the produced potential variations to thecontrol electrode of the second electron discharge tube, means includingan adjustable impedance for maintaining the anode of the second electrondischarge tube positive with respect to its associated cathode, acondenser connected between the anode of the second electron dischargetube and a. point of fixed potential whereby the, condenser may berelatively slowly charged through the adjustable impedanceandsubstantially. instantaneously discharged by said second electrondischarge tube, a first and second unilateral conducting deviceindividually associated with the anode circuit of the electron dischargetubes to normally assure a substantially non-conducting condition of thefirst electron discharge tube and a normally conducting condition of thesecond electron discharge tube thereby assuring aperiodic operation ofthe deflection generator to produce a single sweep potential variationcycle at the anode of the second electron discharge tube a 3 in responseto each applied triggering impulse to the first electron discharge tube.

9. A single sweep deflection generator including a first and secondelectron discharge tube, each tube including a cathode, a controlelectrode and an anode, means for maintaining the cathodes atsubstantially the same potential, means for applying a triggeringimpulse to the control electrode of the first electron discharge tube toproduce a corresponding potential variation at the anode of said tube,means for applying the produced potential variation to the controlelectrode of the second electron discharge tube, means including animpedance for maintaining the anode of the second electron dischargetube positive with respect to its associated cathode, a condenserconnected between the anode of the second electron discharge tube and apoint of fixed potential whereby the condenser may be slowly chargedthrough said impedance and quickly discharged by said second electrondischarge tube, a unilateral conducting device effectivzely connected inparallel with said impedance to assure aperiodic operation and tonormally maintain a conducting condition of the second electrondischarge tube so that upon the application of a triggering impulse tothe control electrode of the first electron dischargetube the condenserassociated with said second electron discharge tube will be charged to apredetermined potential level and will immediately be discharged by saidsecond electron discharge tube to produce a single sweep deflectioncycle across said condenser.

10. A single sweep deflection generator including a pair of electrondischarge tubes each including an anode, a control electrode and acathode, means for applying triggering impulses eX- tending in apredetermined potential direction to the control electrode of one ofsaid tubes to produce a voltage variation extending in a predetermineddirection, means to maintain the oathodes of the two tubes atsubstantially the same potential, means to apply the produced voltagevariations to the control electrode of the other electron dischargetube, a condenser connected between the anode of the said other electrondischarge tube and a point of fixed potential, an adjustable chargingresistance and source of positive potential associated with saidcondenser so that the condenser may be gradually charged through saidresistance and quickly discharged by said other electron discharge tubein response to an applied voltage variation, means including aunilateral conducting device effectively connected in parallel with theanode circuit of each electron discharge tube to assure aperiodicoperation of the deflection generator so that the condenser is chargedand immediately discharged upon the application of each individualtriggering impulse.

LESTER C. SMITH.

